The goal of this research project is to advance rapidly the current genetic research on autism. I suggest that the existing results of genetic (i.e., genome screen) studies have been less definitive because of the heterogeneity among persons with autistic spectrum disorders. Even when diagnosed according to strict and consistent criteria (e.g., the Autism Diagnostic Inventory), symptom profiles of persons with autism vary greatly, suggesting variability in etiology. Thus, I propose to identify and validate a putative subtype of autism, which I refer to as "developmental verbal dyspraxia." Developmental verbal dyspraxia (DVD) is a motor-speech programming disorder resulting in difficulty coordinating and sequencing the oral-motor movements necessary to produce and combine speech sounds (phonemes) to form syllables, words, phrases, and sentences. I hypothesize that a sizable minority of minimally or nonverbal persons with autism are characterized by developmental verbal dyspraxia. Support for my hypothesis comes from behavioral, genetic, and neuroanatomical evidence. In ongoing research (in collaboration with Hill Goldsmith) I am identifying and validating a DVD subtype of autism by screening all children with autism (under age 18) in a metropolitan area; identifying the members of this group who are also characterized by DVD; selecting an autism control group of children not characterized by DVD and a typically developing control group; collecting extensive behavioral, medical, and developmental histories of all children in these groups; obtaining neuroanatomical (structural MRI) data; and collecting and storing DNA. The goal of the research training for this fellowship is to construct indices of the DVD subtype from the diagnostic instruments that have been used in the previously conducted genome screens (e.g., the ADI and A-DOS) and apply those indices to the existing screen data to identify candidate gene regions for the autism-DVD subtype.